The overall objective of the proposed research is to understand the mechanisms of cell-specific gene expression. To achieve this goal we propose to investigate the regulation of the synthesis of sperm-specific proteins in Caenorhabditis elegans by both genetic and biochemical techniques. The basic plan is to isolate spermatogenesis mutants and characterize them by immunocytochemical and electrophoretic techniques to determine which sperm proteins are affected by which mutations. Then by immunocytochemical and recombinant DNA techniques it will be determined whether the various mutations cause transcriptional or post- transcriptional blocks to the expression of different genes involved in spermatogenesis. Using monoclonal antibodies to sperm proteins and two-dimensional gel electrophoresis, the temporal and spatial regulation of sperm-specific proteins will be determined in both wild-type and spermatogenesis mutants. Mutations affecting sperm-specific functions will be isolated and complementation tests will be done to determine the number of spermatogenesis-specific genes. These mutants will be characterized as to which sperm proteins are affected by the different mutations. Recombinant DNA molecules containing spermatogenesis-specific sequences have been selected and will be used as in situ and in vitro probes to determine the transcriptional or post-transcriptional regulation for differnt sperm proteins. Our major efforts will be concerned on the genes for the major sperm protein 15K which we have cloned and sequenced. We will determine the number of actively transcribed MSP genes, their arrangement in the genome, and the molecular basis for their expression.